Currently, the wafer level chip size packaging (WLCSP) technology is the mainstream semiconductor chip packaging technology, in which a full wafer is packaged and tested, and then is cut to acquire individual finished chips. By using this packaging technology, the individual packaged chip product almost has the same size as an individual crystalline grain, which meets the market requirement for lighter, smaller, shorter, thinner and cheaper microelectronic products. The wafer level chip size packaging technology is a hotspot in the current packaging field, and represents a development trend in the future.